Board Looking Into Why Members Weren't Informed of Troubles With Small Cars Stalling

General Motors Co.'s board has stepped up its response to the controversy over the auto maker's handling of vehicle safety recalls, hiring a law firm to review how information about potentially dangerous defects flowed to its members.

Directors at the largest U.S. auto maker weren't previously apprised of the troubles with small cars stalling due to a faulty ignition-switch, according to a person close the board. They want their...